This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A121970 #18 Jun 08 2025 15:11:24
%S A121970 459,1467,1692,3285,8019,14967,16992,23706,23769,24894,26496,32796,
%T A121970 32985,37206,40698,44397,45207,49599,62298,80199,80919,104697,106992,
%U A121970 108729,108972,127809,134667,135378,135774,136818,136962,145827,147492
%N A121970 Numbers k such that if you subtract k from its reversal you get a positive number with the same digits as k.
%C A121970 If negative numbers are included then the sequence is the above together with its reversals. - _Robert G. Wilson v_, Sep 11 2006
%H A121970 Harvey P. Dale, <a href="/A121970/b121970.txt">Table of n, a(n) for n = 1..1000</a>
%H A121970 Kevin Browne, <a href="http://www.mathpages.com/home/kmath136/kmath136.htm">Subtracting the Reversal</a>.
%e A121970 459 is a member because 954 - 459 = 495; 16992 is a member because 29961 - 16992 = 12969.
%t A121970 Select[Table[n, {n, 200000}], ToExpression[StringReverse[ToString[ # ]]] - # > 0 && Sort[IntegerDigits[ # ]] == Sort[IntegerDigits[ToExpression[StringReverse[ToString[ # ]]] - # ]] &]
%t A121970 fQ[n_] := Block[{id = IntegerDigits@n}, rev = FromDigits@ Reverse@id; rev > n && Sort@id == Sort@IntegerDigits[rev - n]]; Select[ Range@153971, fQ@# &] (* _Robert G. Wilson v_, Sep 11 2006 *)
%t A121970 Select[Range[150000],With[{c=IntegerReverse[#]-#},c>0&&Sort[IntegerDigits[c]]==Sort[IntegerDigits[#]]&]] (* _Harvey P. Dale_, Jun 07 2025 *)
%Y A121970 Cf. A055161, A121969.
%K A121970 base,nonn
%O A121970 1,1
%A A121970 _Tanya Khovanova_, Sep 04 2006